1. Field of the Invention
The present invention relates to a vacuum suction adjustable transfer roller, and in particular to a vacuum suction adjustable transfer roller and a film attachment method using the transfer roller.
2. The Related Arts
Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus of wide applications, such as mobile phones, personal digital assistants (PDAs), digital cameras, computer monitors, and notebook computer screens.
Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise an enclosure, a liquid crystal panel arranged in the enclosure, and a backlight module mounted in the enclosure. The structure of a conventional liquid crystal panel is composed of a color filter (CF) substrate, a thin-film transistor (TFT) array substrate, and a liquid crystal layer arranged between the two substrates and the principle of operation is that a driving voltage is applied to the two glass substrates to control rotation of the liquid crystal molecules of the liquid crystal layer in order to refract out light emitting from the backlight module for generating images. Since the liquid crystal panel itself does not emit light, light must be provided from the backlight module in order to normally display images. Thus, the backlight module is one of the key components of the liquid crystal displays. The backlight modules can be classified in two types, namely a side-edge backlight module and a direct backlight module, according to the site where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal panel to form a planar light source directly supplied to the liquid crystal display panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to pass through an optic film assembly so as to form a planar light source for the liquid crystal display panel.
The two substrates that constitute the conventional liquid crystal display panel are both provided with various optic films attached thereto, such as polarization films and brightness enhancement films, in order to enhance the effect of displaying.
The optic film attachment methods that have been heretofore used are performed through press-to-attach to a substrate by means of a transfer roller. A displaying panel that enables 3D displaying by attaching a 3D film to a substrate is being widely used, in which the attachment of the 3D film is also achieved by using a transfer roller to press and attach the 3D film to the substrate. Specifically, the transfer roller uses a special adhesive layer having adhesion to hold the 3D film thereon and then, presses and attaches the 3D film to the substrate. However, the special adhesive layer having adhesion has a predetermined lifespan and must be periodically replaced. Further, the adhesion of the special adhesive layer is generally impossible to control. Consequently, to ensure the 3D film can be effectively pressed and attached to the substrate, the pressure that the transfer roller applies to the substrate must be set as a pressure that ensures achievement of the attachment of the 3D film for the situation that the special adhesive layer having adhesion shows the maximum of the adhesion. This, however, may pose an increased pressure applied to the substrate. Such a pressure may cause a potential risk of breaking the substrate when the substrate is relatively thin (especially when the thickness of the substrate is less than or equal to 0.5 mm).